Introduction to Electronics and Introduction to Electronics and Breadboard CircuitsBreadboard Circuits

What we're going to learn:What we're going to learn:

What is an electronic circuit?What kind of power is needed for these projects?What are the fundamental principles of electronics?What are the basic electronic components used in DC analog circuits?How do these principles combine to make interesting things? We're going to make some of those things, and you can take the kit, and the projects home with you.

Electricity can be broken down Electricity can be broken down into:into:

Electric Charge VoltageCurrentResistance

Negative & Positive ChargesNegative & Positive Charges

What do the effects of electricity in TV, radio, a battery, and lightening all have in common?

Basic particles of electric charge with opposite polarities.

ElectronsElectrons

The smallest amount of electrical charge having the quality called negative polarity.

Electrons orbit the center of atoms.

ProtonsProtons

The proton is a basic particle with positive polarity.

Protons are located in the nucleus of atoms along with neutrons, particles which have neutral polarity.

Electrically, all materials fall into Electrically, all materials fall into 1 of 3 classifications:1 of 3 classifications:

ConductorsInsulators Semi-Conductors

Conductors Conductors

Have 1 valence electronMaterials in which electrons can move

freely from atom to atom are called conductors.

In general all metals are good conductors. The purpose of conductors is to allow

electrical current to flow with minimum resistance.

InsulatorsInsulators

Have 8 valence electronsMaterials in which electrons tend to stay put

and do not flow easily from atom to atom are termed insulators.

Insulators are used to prevent the flow of electricity.

Insulating materials such as glass, rubber, or plastic are also called dielectrics, meaning they can store charges.

Dielectric materials are used in components like capacitors which must store electric charges.

Semi-ConductorsSemi-Conductors

Have 4 valence electronsMaterials which are neither conductors nor

insulators Common semi conductor materials are

carbon, germanium and silicone.Used in components like transistors

The Symbol for ChargeThe Symbol for Charge

The symbol for charge is Q which stands for quantity.

The practical unit of charge is called the coulomb (C).

One coulomb is equal to the amount of charge of 6.25X1018 electrons or protons stored in a dielectric.

Harnessing ElectricityHarnessing Electricity

First we must separate the + & - charges in matter.

Changing the balance of forces produces evidence of electricity.

Example: A battery. Its chemical energy separates electric charges to produce an excess of electrons on one lead, and an excess of protons on the other.

VoltageVoltage

Potential refers to the possibility of doing work.

Any charge has the potential to do the work of attracting a similar charge or repulsing an opposite charge.

The symbol for potential difference is E (for electromotive force)

The practical unit of potential difference is the volt (V)

1 volt is a measure of the amount of work required to move 1C of charge

CurrentCurrent

When a charge is forced to move because of a potential difference (voltage) current is produced.

In conductors - free electrons can be forced to move with relative ease, since they require little work to be moved.

So current is charge in motion.The more electrons in motion the greater

the current.

AmpereAmpere

Current indicates the intensity of the electricity in motion. The symbol for current is I (for intensity) and is measured in ampere.

The definition of current is: I = Q/T Where I is current in ampere, Q is charge

in coulomb, and T is time in second.

1 ampere = 1 coulomb per second1 ampere = 1 coulomb per second

ResistanceResistance

Opposition to the flow of current is termed resistance.

The fact that a wire can become hot from the flow of current is evidence of resistance.

Conductors have very little resistance.Insulators have large amounts of

resistance.

OhmsOhms

The practical unit of resistance is the ohm designated by the Greek letter omega: Ω

A resistor is an electronic component designed specifically to provide resistance.

Ohm’s lawOhm’s lawCurrent = voltage / resistance I = V / R V = I x R

Definitions Voltage = potential energy / unit charge, units = Volts Current = charge flow rate, units = Amps Resistance = friction, units = Ohms

Example Voltage drop when current flows through resistor V1 - V2 = I R

IR

V1

V2

Schematics Schematics Symbols represent circuit elements Lines are wires

+ Battery

Resistor

Ground

+V

RI

Sample circuit

Ground voltagedefined = 0

Basic ComponentsBasic Components

Parallel and series resistorsParallel and series resistorsSeries same current flows through allParallel save voltage across all

+

Note: these points are connected together

I

VR1

R2

Series circuitV = R1 I + R2 I = Reff IReff = R1 + R2

Parallel circuitI = V/R1 + V/R2 = V/Reff 1/Reff = 1/R1 + 1/R2

+V

R1R2I1 I2

I

Resistive voltage dividerResistive voltage divider Series resistor circuit Reduce input voltage to desired level Advantages:

simple and accurate complex circuit can use single voltage source

Disadvantage: dissipates power easy to overload need Rload << R2

New schematic symbol:external connection

+

Vin

R1

R2 I

IVout

Resistive dividerI = Vin/Reff = Vout/R2

Vout = Vin (R2 / (R1 + R2) )

Variable voltage dividerVariable voltage divider

Use potentiometer (= variable resistor) Most common: constant output resistance

+

Vin Rvar

Rout I

IVout

Variable voltage dividerVout = Vin (Rout / (Rvar + Rout) )

New schematic symbol:potentiometer

Capacitors Capacitors Charge = voltage x capacitance Q = C VDefinitions Charge = integrated current flow , units = Coloumbs = Amp - seconds I = dQ/dt Capacitance = storage capacity, units = FaradsExample Capacitor charging circuit Time constant = RC =

Capacitor charging circuitV = VR + VC = R dQ/dt + Q/CdQ/dt + Q/RC = V/RQ = C V (1 - exp(-t/RC))Vout = Vin (1 - exp(-t/RC))

New schematic symbol:capacitor

+V R

C

IVout

Q

Vout

t

Vin

= RC

Capacitor charging curvetime constant = RC

AC circuitsAC circuits Replace battery with sine (cosine) wave

source V = V0 cos(2 f t)Definitions Frequency f = cosine wave frequency, units =

Hertz Examples Resistor response: I = (V0/R) cos(2 f t) Capacitor response: Q = CV0 cos(2 f t)

I = - 2 f CV0 sin(2 f t) Current depends on frequency negative sine wave replaces cosine wave - 90 degree phase shift = lag

V0 cos(2 f t)

RI = (V0/R) cos(2 f t)

Resistive ac circuit

New schematic symbol:AC voltage source

V0 cos(2 f t)

CI =

- 2 f CV0 sin(2 f t)

Capacitive ac circuit• 90 degree phase lag

Simplified notation: ac-circuitsSimplified notation: ac-circuits V = V0 cos(2 f t) = V0 [exp(2 j f t) + c.c.]/2 Drop c.c. part and factor of 1/2 V = V0 exp(2 j f t) Revisit resistive and capacitive circuits Resistor response: I = (V0/R) exp(2 j f t) = V / R = V/ ZR Capacitor response: I = 2 j f CV0 exp(2 j f t) = (2 j f C) V =

V/ ZC Definition: Impedance, Z = effective resistance, units Ohms Capacitor impedance ZC = 1 / (2 jf C) Resistor impedance ZR = RImpedance makes it look like Ohms law applies to capacitive

circuits also Capacitor response I = V / ZC

Explore capacitor circuitsExplore capacitor circuitsImpedance ZC = 1/ (2 jf C) Limit of low frequency f ~ 0

ZC --> infinity Capacitor is open circuit at low frequency

Limit of low frequency f ~ infinity ZC --> 0 Capacitor is short circuit at low frequency

V0 cos(2 f t)

CI = V/ZC

Capacitive ac circuit

Revisit capacitor charging Revisit capacitor charging circuitcircuitReplace C with impedance ZC Charging circuit looks like voltage divider Vout = Vin (ZC / (ZR + ZC) ) = Vin / (1 + 2 jf R C )Low-pass filterCrossover when f = 1 / 2 R C = 1 / 2 , is time

constant lower frequencies Vout ~ Vin = pass band higher frequencies Vout ~ Vin / (2 jf R C ) =

attenuated

Capacitor charging circuit= Low-pass filter

Vin = V0 cos(2 f t)

R

C

IVout

Ilog(Vout)

log(f )

logVin

f = 1 / 2

Low-pass filter response• time constant = RC =

Single-pole rolloff6 dB/octave= 10 dB/decade

knee

Inductors Inductors Voltage = rate of voltage change x inductance V = L dI/dtDefinitions Inductance L = resistance to current change, units = HenrysImpedance of inductor: ZL = (2 jf L) Low frequency = short circuit High frequency = open circuitInductors rarely used

Capacitor charging circuit= Low-pass filter

Vout

log(Vout)

log(f )

logVin

f = R / 2 jL

High-pass filter response

Vin = V0 cos(2 f t)

RL

I

INew schematic symbol:Inductor

Capacitor filters circuitsCapacitor filters circuits Can make both low and high pass filters

Low-pass filterVin = V0 cos(2 f t)

RC

IVout

I

High-pass filterVin = V0 cos(2 f t)

CR

IVout

I

log(Vout)

log(f )

logVin

f = 1 / 2

Gain response

log(Vout)

log(f )

logVin

f = 1 / 2

Gain response

knee

phase

log(f )

f = 1 / 2

Phase response

-90 degrees

phase

log(f )

f = 1 / 2

Phase response

-90 degrees

0 degrees 0 degrees

Summary of schematic symbolsSummary of schematic symbols

+Battery Resistor

Ground

Externalconnection

Capacitor AC voltagesource

Inductor

Non-connecting wires -

+

Op amp

Potentiometer

Potentiometer2-inputs plus

center tap

Diode

Closed CircuitsClosed Circuits

In applications requiring the use of current, electrical components are arranged in the form of a circuit.

A circuit is defined as a path for current flow.

A Simple CircuitA Simple Circuit

Common Electronic Component Common Electronic Component SymbolsSymbols

A Complex Audio CircuitA Complex Audio Circuit

Open CircuitsOpen Circuits

The Circuit is a Load on the The Circuit is a Load on the Voltage SourceVoltage Source

The circuit is where the energy of the source (battery) is carried by means of the current through the the various components.

The battery is the source, since it provides the potential energy to be used.

The circuit components are the load resistance - they determines how much current the source will produce.

Direction of Electron FlowDirection of Electron Flow

The direction of electron flow in our circuit is from the negative side of the battery, through the load resistance, back to the positive side of the battery.

Inside the battery, electrons move to the negative terminal due to chemical action, maintaining the potential across the leads.

Electron Flow in a Simple CircuitElectron Flow in a Simple Circuit

DCDC

Circuits that are powered by battery sources are termed direct current circuits.

This is because the battery maintains the same polarity of output voltage. The plus and minus sides remain constant.

Waveform of DC VoltageWaveform of DC Voltage

Characteristics of DCCharacteristics of DC

It is the flow of charges in just one direction and...

The fixed polarity of the applied voltage which are characteristics of DC circuits

ACAC

An alternating voltage source periodically alternates or reverses in polarity.

The resulting current, therefore, periodically reverses in direction.

The power outlet in your home is 60 cycle ac - meaning the voltage polarity and current direction go through 60 cycles of reversal per second.

All audio signals are AC also.

Waveform of AC VoltageWaveform of AC Voltage

Complex VoltageComplex Voltage

This is a more realistic view of what an audio signal’s voltage would look like

Comparison of DC & ACComparison of DC & ACDC VoltageDC Voltage AC VoltageAC Voltage

Fixed polarityFixed polarity Reverses polarityReverses polarity

Can be steady or vary in Can be steady or vary in magnitudemagnitude

Varies in magnitude Varies in magnitude between reversals in between reversals in polaritypolarity

Steady value cannot be Steady value cannot be stepped up or down by a stepped up or down by a transformertransformer

Used for electrical power Used for electrical power distributiondistribution

Electrode voltage for tube Electrode voltage for tube and transistor ampsand transistor amps

I/O signal for tube and I/O signal for tube and transistor ampstransistor amps

Easier to measureEasier to measure Easier to amplifyEasier to amplify

Heating Effects the same for both AC and DC current

Many Circuits Include both AC & Many Circuits Include both AC & DC VoltagesDC Voltages

DC circuits are usually simpler than AC circuits.

However, the principles of DC circuits also apply to AC circuits.

ImpedanceImpedance

Impedance is resistance to current flow in AC circuits and its symbol is .

Impedance is also measured in ohms.

Grounding Grounding

In the wiring of practical circuits one side of the voltage source is usually grounded for safety.

For 120 V - ac power lines in homes this means one side of the voltage source is connected to a metal cold water pipe.

For electronic equipment, the ground just indicates a metal chassis, which is used as a common return for connections to the source.

Linear Proportion Between E and I Linear Proportion Between E and I for a Constant Resistancefor a Constant Resistance

OHM’s LAWOHM’s LAW

PowerPower

The unit of electrical power is the watt.Power is how much work is done over

time.One watt of power is equal to the work

done in one second by one volt moving one coulomb of charge. Since one coulomb a second is an ampere:

Power in watts = volts x amperesP = E x I

3 Power Formulas3 Power Formulas

P = E x IP = I2 x RP = E2 / R

Conversion FactorsConversion Factors

PrefixPrefix SymbolSymbol Relation to Relation to basic unitbasic unit

ExamplesExamples

MegaMega MM 1,000,000 1,000,000 or 1x10or 1x1066

5MΩ =5MΩ =

5x105x106 6 ΩΩ

KiloKilo kk 1,000 or1,000 or

1x101x1033

18kV =18kV =

18x1018x1033 V V

MilliMilli mm .001 or .001 or

1x101x10-3-3

48 mA = 48 mA =

48x1048x10-3-3AA

MicroMicro .000001 or.000001 or

1x101x10-6-6

1515V =V =

15x1015x10-6-6VV

About partsAbout parts

Symmetric vs AsymmetricPolarizedPhysics and chemistry in a tiny packageExplain Data Sheets

What is electricity?What is electricity?

What kinds are there?What can it do?What are the dangers?

What is a circuit?What is a circuit?

Combination of electronic parts, wires connected between power sources. It's like a physical program. It's also like setting up dominoes in sequence.

What is a breadboard?What is a breadboard?

What are they good for?Creatings, organizing, and prototyping a circuit.

Literally started out as a bread board with nails.

What are LEDs?What are LEDs?

Light Emitting DiodesDiode Symbol + Arrows for lightPoints to ground

Hello World for a CircuitHello World for a Circuit

Light and LEDParts:BatteryResistorLED

Why:Power SourceAn LED will light up when enough voltage is supplied but can also burn out if too much is allowed to pass through. The resistor will limit the voltage to prevent damage.

Do:Connect Battery, Resistor, LED

LED CircuitLED Circuit

1 LED Plus resistorWhy have a resistor?Current, limiting.

Series circuit exampleSeries circuit example

Parallel Circuit exampleParallel Circuit example

Parallel and Series Circuit ExampleParallel and Series Circuit Example

Fundamental PartsFundamental Parts

ResistorCapacitorWireDiodesLight Emitting Diodes (LED)BatteryTransistorsMotorsThey each have a physical property that interacts with electricity. When put in combination various actions occur.

What are resistors?What are resistors?

Resistors provide a specific amount of resistance to a path in a circuit or wire. Ohm's law is used to calculate the properties related to resistance.

Ohm's Law: I = V/RI = Current measured in AmpsV = Voltage measured in VoltsR = Resistance measured in Ohms

Resistors are color coded.

Resistor Color CodeResistor Color Code

Resistor Color Code Wheel Calculator

Variable resistor: The potentiometerVariable resistor: The potentiometer

Voltage dividersTry out the different pots.

RGB LEDRGB LED

Try resistors out in various combination to make different colors. Experiment by adding potentiometers to the leads.

LED and PhotoresistorLED and Photoresistor

Photoresistors change their resistance by the amount of light detected.

What are capacitors?What are capacitors?

Capacitor is two separated charges.Known charge up time.Know discharge time.Two major kinds• Electrolytic, asymmetric, bipolar • Ceramic, symmetric

Capacitors in seriesCapacitors in series

Capacitors in ParallelCapacitors in Parallel

They can provide energy, however briefly.They can smooth out a signal.

Attach the battery briefly to fill the capacitor.

Capacitors in series and parallelCapacitors in series and parallel

Make a voltage regulatorMake a voltage regulator

Turn things on and off with a:Turn things on and off with a:

WireButtonPhotoresistorHall Effect SensorRelayTransistorButtonSwitch

TransistorsTransistors

NPN Transistor

Hall Effect SensorHall Effect Sensor

Reed Switch ExampleReed Switch Example

A reed switch is closed when a magnet is in close proximity.It is symmetric so it can placed either direction.

Tilt ball switchTilt ball switch

Emergency on/off if project tips over.

MotorsMotors

Try changing the direction of the diode.What happens?

RelayRelay